Re: [HTCondor-users] How to tie slots to cpus ?

[Greg Thain <gthain@xxxxxxxxxxx>]

On 9/3/21 12:21 AM, Valerio Bellizzomi wrote:
> Greetings,
>
> on a htcondor execute machine with 2 cpus how do I tie slots to cpus ?

Good morning:

I'm not quite sure what is meant by "tie"ing a slot to a cpu. If you 
absolutely want to lock a specific cpu core to a slot, you can configure 
partitionable slots, and set ASSIGN_CPU_AFFINITY = true, and HTCondor 
will use OS mechanisms to pick affinity-bind cpu cores to slots. We 
generally don't recommend this, because, while all processes in this job 
will be locked onto this cpu, HTCondor can't control if processes 
outside it's control will run on that cpu.

On Linux, if HTCondor is running as root, it will, by default, use 
cgroups to constrain the total cpu used by a job to the number of cores 
in the slot the job lands on. This is better, as the job isn't locked 
to any particular cpu, and if the Linux cpu schedule does it job 
properly, the overall system throughput should be better.


-greg